Thread: DI on trolling motor

I didn't know DI worked best when the boat was moving. I thought you got a good picture just barely moving or settiing still. If this is the case, will the DI have any problems mounted on the transom. Is this true with Structure Scan als????Thanks

Originally Posted by crappie1133

I didn't know DI worked best when the boat was moving. I thought you got a good picture just barely moving or settiing still. If this is the case, will the DI have any problems mounted on the transom. Is this true with Structure Scan als????Thanks

It's important to understand how the unit takes the acoustic sonar pulses (pings) and makes the DI screen display image....

The DI sonar beam is very thin front to back but very wide side to side...

As the Xducer "pings", a single sound pulse is sent thru the water and then reflects off objects in that sonar beam's shape...

When that single "ping" returns to the unit, the reflected data is processed and then plotted onto the screen in the very first couple of pixel rows on the right-most edge of the screen...

There can only be one (1) DI sonar "ping" in the water at a time so the unit has to wait for the return reflected "ping" before it can send out the next "ping"..

The very next "ping" that is sent and received is then processed and plotted on the right-most edge of the screen and subsequently "pushes" the previous "ping" data to the left on the screen...

It is this "pinging", reflecting, receiving, processing, plotting sequence that creates the "scrolling" effect seen on the DI screen display...

It is the forward movement of the boat that allows each successive "ping" to process a new "slice" of water in order to keep from "pinging" the same slice of water "over and over"...

DI will indeed work sitting perfectly still but the image created on the DI display will just be a lot of long "streaks" moving across the screen as the unit "pings" the same fish "over and over" or the same section of brush "over and over"...

Rickie

Thanks, rickie. Very helpful and understandable. how much (or how fast) do you need to move? Thanks again!!

Originally Posted by crappie1133

Thanks, rickie. Very helpful and understandable. how much (or how fast) do you need to move? Thanks again!!

The general consensus is to adjust the chart speed to match your boat speed..

Scanning at 1mph or slower use a chart speed of 1...
Scanning at 2mph use a chart speed of 2...
Scanning at 3mph use a chart speed of 3.....
Etc...

Rickie

Originally Posted by rnvinc

DI will indeed work sitting perfectly still but the image created on the DI display will just be a lot of long "streaks" moving across the screen as the unit "pings" the same fish "over and over" or the same section of brush "over and over"...

Rickie

Rickie is quite correct .... as seen in this picture of my Elite 5DSI showing the edge of a brush pile, while the boat was sitting still ---



... cp

Originally Posted by crappie1133

I didn't know DI worked best when the boat was moving. I thought you got a good picture just barely moving or settiing still. If this is the case, will the DI have any problems mounted on the transom. Is this true with Structure Scan als????Thanks

I think DI on the tm is the best thing since pockets on bibbed overalls .

Here is a link to some screen shots I took at speeds as low as 0.6 mph, these were using a Lowrance Gen-1 HDS 8 and a LSS-1. They are not as clear as a 3-4 mph shot but very useable IMO.

http://www.crappie.com/crappie/side-...-shots-tm.html